(1) Field of the Invention
The present invention relates to a VTR (Video Tape Recorder) and relates particularly to a tape loading apparatus which can load and unload magnetic tapes utilizing a loading ring.
(2) Background Art
A tape loading apparatus using a loading ring generally includes a motor by means of which a tape loading ring is rotated by means of a rotational transmission mechanism to carry out tape loading and unloading. Generally such an apparatus engages an epicyclic gear to effect tape loading.
A conventional rotational transmission mechanism generally includes: a rubber belt, one end of which is suspended on a rotational axis of a motor; the other end of the rubber belt engages a worm gear; the worm gear meshes with a worm wheel; a pinion gear mounted on the worm wheel meshes with a gear surface provided on an outer circumferential surface of the loading ring. When a rotational axle of the motor is rotated in one direction, the loading ring is rotated in a loading direction (arrow marked direction) via the rubber belt, worm gear, worm wheel, pinion, and gear surface. When the loading ring is rotated to a tape loading end position, a stopper pin installed on a lower surface of the loading ring is contacted with a positioning pin installed on a chassis and the rotation of a loading ring is stopped to complete the tape loading. (Refer to a Japanese Patent Utility Model Registration Second Publication No. Showa58-50516 published on Nov. 17, 1983).
In the above-described tape loading apparatus, a rubber belt is used so that when the stopper pin is contacted with the positioning pin at the chassis side, the belt slips, serving as a so-called limiter. In addition, the worm and worm gear are used as a loading ring mechanism so that the stopper pin is maintained in a state where the stopper pin is pressed against the positioning pin.
The following problems arise in the previously proposed tape loading apparatus:
(1) Since both a worm and worm gear wheel are used, transmission of rotational force from the motor is less efficient.
(2) When utilizing a worm and worm gear wheel, locking of the loading ring is not secure, and a relatively large force must be applied to the loading ring to reverse loading ring direction.
(3) The rubber belt lacks durability, and must be replaced regularly, so maintenance becomes troublesome.
Another tape loading apparatus using an epicylic gear is exemplified by a U.S. Pat. No. 4, 884, 153 issued on Nov. 28, 1989. This loading device is cumbersome and expensive to manufacture as well as being more prone to breakdown than simpler loading devices.